Is the expiation for an oath (kaffarat al-yamin) determined by the day it was sworn and then broken, or is it general, depending on the person's situation? And is it permissible to fast if giving money would lead to the salary not being sufficient until the end of the month?

Fasting is not valid as an expiation unless one is unable to feed, clothe, or free a slave, based on the Almighty's saying: "But whoever finds none - then a fast of three days." Scholars differed on the time of considering this inability: some considered it at the time of the oath-breaking, and therefore fasting would not be sufficient for you if you possess enough money for your sustenance and your family's sustenance for a day and a night after the cost of feeding or clothing. Others permitted fasting for those who are eligible for zakat.